Like many other posts, I too unfortunately have experienced missing items and characters.
I can’t see the logic in why, but it does happen. I started playing as of patch 2.6 on Xbox, offline mode.
This is a serious problem for any game to have, especially D2 where the whole objective is character levelling are hard to get items. It’s such a shame as the game is very good, but yet at risk of undoing all your progress for an unknown reason.
Please try and fix team